Visually impairing cataract, or clouding of the lens, is the leading cause of preventable blindness in the world. An accepted treatment for cataracts is surgical removal of the affected lens and replacement with an artificial intraocular lens (“IOL”). Cataract extractions are among the most commonly performed operations in the world.
FIG. 1 is a diagram of an eye 10 showing some of the anatomical structures related to the surgical removal of cataracts and the implantation of IOLs. The eye 10 comprises a lens 12, an optically clear cornea 14, and an iris 16. A lens capsule 18, located behind the iris 16 of the eye 10, contains the lens 12, which is seated between an anterior capsule segment or anterior capsule 20 and a posterior capsular segment or posterior capsule 22. The anterior capsule 20 and the posterior capsule 22 meet at an equatorial region of the lens capsule 18. The eye 10 also comprises an anterior chamber 24 located in front of the iris 16 and a posterior chamber 26 located between the iris 16 and the lens capsule 18.
The eye 10 functions to provide vision by transmitting light through the cornea 14, and focusing the image by way of the lens 10 onto a retina 25. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea 14 and the lens 10. When age or disease causes the lens to become less transparent or opacified, vision deteriorates because of the diminished light which may be transmitted to the retina 25. The cataract is this deficiency in the lens 10.
A common technique of cataract surgery known as extracapsular cataract extraction (“ECCE”) involves the creation of an incision 30 near the outer edge of the cornea 14 and an opening in the anterior capsule 20 (i.e., an anterior capsulotomy) through which the opacified lens 12 is removed. The lens 12 can be removed by various known methods including phacoemulsification, in which ultrasonic energy is applied to the lens 12 to break it into small pieces that are promptly aspirated from the lens capsule 18.
A common complication of phacoemulsification procedures arises from a blockage or occlusion of the aspirating needle. As the irrigation fluid and emulsified tissue is aspirated away from the interior of the eye through the hollow cutting needle, pieces of emulsified tissue may become at least momentarily lodged in the aspirating lumen. Such blockages may cause undesirable pressure changes in the eye and/or the handpiece. For example, when the aspiration lumen is clogged, vacuum pressure may rapidly increase within the lumen. After the clog is removed, the resulting drop in anterior chamber pressure is known as post-occlusion surge, which can cause a large quantity of fluid and tissue to be aspirated out of the eye too quickly, potentially causing the eye to collapse and/or causing the lens capsule 18 to be torn.
Various equipment designs and methods have been derived in order to minimize the problems introduced by a blocked aspiration lumen during a phacoemulsification procedure or other cataract removal procedure. However, there remains a need for devices, systems, and methods to more effectively prevent or minimize these blockages. The devices, systems, and methods disclosed herein overcome one or more of the deficiencies of the prior art.